TW201438847A - Method for manufacturing glass substrate and method for manufacturing glass substrate for display - Google Patents

Abstract

This invention may inhibit the generation of dust particles in the subsequent steps by cleaning the end face of a glass substrate to remove residues on the end face. The method for manufacturing a glass substrate of this invention is a method for manufacturing a glass panel provided with a grinding processed part that has been subjected to a grinding process. The processed part is grinded by contacting magnet grinding particles. Acidic cleaning solution is supplied to the grinded processed part, such that the processed part and the surface of the magnet attached on the processed part are charged with the same polarity, so that the processed part and the magnet are repulsed by each other to make the metal attachments move to the acidic cleaning solution.

Description

Method for producing glass substrate and method for producing glass substrate for display

The present invention relates to a method for producing a glass substrate for a display which is characterized in the end surface treatment of a glass substrate.

The manufacturing step of the display panel such as a liquid crystal display panel and the glass substrate for a display includes a step of chamfering the end surface formed by cutting the glass substrate. The end surface of the glass substrate was ground by a diamond grinding wheel to remove cracks and sharp edges caused by the cutting. For example, the shape is adjusted in such a manner that the cross section becomes an R shape by using a diamond grinding wheel. Thereafter, the end surface of the glass substrate is polished by using a polishing process of a flexible polishing wheel containing, for example, a foamed resin.

Further, as a polishing processing technique, a technique in which a polishing slurry containing a magnetic material is used for polishing a glass substrate end surface as described in Patent Document 1 is known. Further, a technique of using a polishing slurry containing a magnetic material for mirror surface processing as described in Patent Documents 2 and 3 is known.

Moreover, for the polished glass substrate, it is necessary to remove the glass frit and the attached abrasive material and abrasive particles generated during the polishing process from the glass substrate by cleaning the front surface (main surface) and the end surface of the glass substrate. .

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2012/067587

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-83827

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2000-233359

In recent years, as the display panel has been developed in the direction of high definition and high resolution, the thinning of the TFT line width is required for the driving panel side, and the thinning of the black matrix is further required for the color filter panel side. In order to cope with such a demand for a glass substrate, a higher cleanliness is required for the surface of the glass substrate.

Accordingly, the present invention provides a method of producing a glass substrate using a technique of cleaning foreign matter adhering to an end surface of a glass substrate by polishing.

One of the main causes of foreign matter adhering to the main surface of the glass substrate is that foreign matter adhering to the end surface of the glass substrate adheres to and remains on the main surface. The end surface of the glass substrate which is mirror-polished by the magnetic abrasive grains may also have foreign matter which cannot be removed by the previous cleaning step.

Therefore, the present invention is a method for producing a glass substrate having a processed portion to be polished, and the processing portion is polished by being brought into contact with a polishing slurry containing a magnetic material, and a cleaning liquid is supplied to the polished processing portion. The surface of the processing unit is charged with the same polarity as the surface of the magnetic body to which the processing unit is attached, and the processing unit and the magnetic body are mutually repelled, and the magnetic body is moved into the cleaning liquid. For example, in the glass substrate having the end surface polished by the magnetic abrasive grains, the end surface of the glass substrate and the end surface are provided by supplying an acidic cleaning liquid, preferably a cleaning liquid containing an organic acid, to the polished end surface. The surface of the attached magnetic abrasive grains, that is, the iron-based fine particles, is charged with the same polarity, and the end face and the iron-based fine particles are mutually repelled, so that the iron-based fine particles are moved to the clear In the lotion.

Moreover, the present invention provides a method for producing a glass substrate for a display, which comprises the following steps as a method of removing magnetic abrasive grains attached to an end surface of a glass substrate polished by magnetic abrasive grains, the step being at a specific pH value In the environment, the surface of the magnetic abrasive grains adhered to the end surface of the glass substrate is ionized, and the surface potential of the end surface of the glass substrate is made to be a positive potential, and the magnetic abrasive grains are floated from the end surface of the glass substrate, and by chelation The magnetic abrasive grains are prevented from adhering again to the main surface and the end surface of the glass substrate, and the magnetic abrasive grains are removed from the glass substrate. Further, in the glass substrate, after the end surface treatment step and the cleaning step, the main surface and the end surface of the glass substrate which are subjected to the alkaline cleaning agent or the like are cleaned by the rinsing step of the end surface.

Moreover, the method for producing a glass substrate of the present invention has a step of forming a glass plate from molten glass, a cutting step of cutting the glass plate to form a glass substrate, and an end surface treatment step by a polishing slurry containing a magnetic body held by the magnetic body is in contact with the end surface of the glass substrate to perform mirror polishing; and a cleaning step of cleaning the above-mentioned surface of the glass substrate by using an acidic chemical solution having a pH of 2 or less The iron-based fine particles generated by the magnetic body; and the cleaning step is characterized in that Fe ³⁺ constituting the iron-based fine particles is reduced to Fe ²⁺ ions, and the above-mentioned Fe ²⁺ ions are complexed to form a fault. Compound.

Moreover, the method for producing a glass substrate for a display according to the present invention has the steps of: forming a glass plate from molten glass; cutting step of cutting the glass plate to form a glass substrate; and an end surface treatment step by The polishing slurry containing the magnetic material held by the magnetic body is brought into contact with the end surface of the glass substrate to perform mirror polishing treatment, and the cleaning step is performed by cleaning the end surface with an acidic chemical solution. The end surface treatment step is a polishing using magnetic abrasive grains, and a magnetic field forming portion including a first magnetic body and a second magnetic body that rotate together with the rotating shaft, and the magnetic abrasive particles and the liquid are formed and formed. a polishing wheel including the polishing slurry of the magnetic material held by a magnetic field between the first magnetic body and the second magnetic body, and the polishing slurry and the glass substrate are rotated while rotating the rotating shaft The end faces are in contact with each other for mirror polishing. Further, the cleaning step is characterized in that a pH of 2 or less, preferably a pH value, is used in order to remove the iron-based fine particles generated by the magnetic abrasive grains adhered to the end surface of the glass substrate in the end surface treatment step. 1.6 or less of the acidic chemical liquid, the Fe ³⁺ constituting the iron-based fine particles is reduced to Fe ²⁺ ions, and two or more of the Fe ²⁺ ions are coordinated to form a complex. Further, the concentration of the magnetic abrasive grains in the polishing slurry used in the mirror polishing treatment is preferably 85 to 95% by weight.

Moreover, the method for producing a glass substrate for a display of the present invention has a cleaning step of supplying a specific pH to the end surface of the glass substrate polished using the magnetic abrasive grains, preferably at a pH of 2 or less, more preferably The acidic chemical liquid having a pH of 1.6 or less is physically cleaned of the above end faces. The acidic chemical solution used in the above washing step is preferably selected from the group consisting of salicylic acid, phthalic acid, glyoxylic acid, oxalic acid, fumaric acid, and maleic acid, which exhibit a chelation effect at a specific pH. Organic acids such as diacid, malonic acid, succinic acid, gluconic acid, trans-aconitic acid, hydroxymalonic acid, lactic acid, pyruvic acid, citric acid, isocitric acid, glycolic acid, malic acid, tartaric acid, etc. Aminocarboxylic acid such as acetic acid, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, amino acid such as serine, aspartic acid, glutamic acid or cysteine One or more of the above-described groups are more preferably selected from the group consisting of two or more of the above groups.

Further, the chemical liquid having a chelation effect used in the washing step of the present invention is preferably a chemical liquid selected from the group consisting of oxalic acid, tartaric acid and citric acid adjusted to have a concentration of 0.5% by weight or more.

According to the method for producing a glass substrate of the present invention and the method for producing a glass substrate for a display, the magnetic body adhered to the end surface of the glass substrate can be removed, and the magnetic body can be prevented from adhering again to the main surface and the end surface of the glass substrate.

30‧‧‧1st face processing machine

31‧‧‧1st grinding wheel

32‧‧‧2nd grinding wheel

33‧‧‧End face of glass substrate G

34‧‧‧2nd face processing machine

35‧‧‧Rotary axis

36‧‧‧Rotary wheel

36a, 36b‧‧‧ magnetic body

37‧‧‧Abrasive slurry containing magnetic material

40‧‧‧ grinding device

60‧‧‧1st end cleaning device

61‧‧‧End face cleaning fixture

61a‧‧‧Rotary axis

61b‧‧‧Support Department

61c‧‧‧cleaning mat

62‧‧‧Transport roller

63, 63a, 63b‧‧‧ end face cleaning nozzle

64‧‧‧2nd face cleaning fixture

64a, 64b‧‧‧ cleaning nozzle

65‧‧‧cleaning roller

70‧‧‧2nd end cleaning device

80‧‧‧Surface cleaning device

100‧‧‧ device

180‧‧‧grinding device

182‧‧‧Rotating wheel

184‧‧‧Supply Department

185‧‧‧ magnetic body

186‧‧Recycling Department

187‧‧‧grinding slurry

200‧‧‧melting device

300‧‧‧Clarification device

400‧‧‧ delivery tube

500‧‧‧Forming device

611‧‧‧cleaning roller

700‧‧‧ liquid tank

800‧‧‧Carmen

G‧‧‧glass substrate

G1‧‧‧Striped glass plate

L‧‧‧Liquid

Fig. 1 is a flow chart showing the steps in the method for producing a glass substrate of the present invention.

Fig. 2 is a schematic view showing the melting step to the cutting step in the present invention.

Fig. 3 is a view showing a state of end surface treatment of the glass substrate of the present invention.

4(a) and 4(b) are views showing a state of polishing processing using the polishing slurry containing a magnetic material of the present invention.

Fig. 5 is a schematic view showing an end face portion of a glass substrate processed by the present invention.

6(a) to 6(c) are views showing the operation of the cleaning device used in the present invention.

7(a) to 7(c) are views showing the operation of the cleaning jig included in the cleaning device used in the present invention.

Fig. 8 is a view showing a state of processing of a glass surface according to another embodiment of the present invention.

Figure 9 is a cross-sectional view showing a part of a batch cleaning system used in the present invention.

Hereinafter, an embodiment of a method for producing a glass substrate of the present invention will be described with reference to the drawings. Furthermore, in the present specification, the glass substrate includes a glass substrate for a display.

(1) Outline of the manufacturing method of the glass substrate

Fig. 1 is a flow chart showing a method of manufacturing a glass substrate of the embodiment. As shown in FIG. 1, the glass substrate is manufactured through the steps of the melting step T1, the forming step T2, the cutting step T3, the end surface processing step T4, the cleaning step T5, and the inspection step T6.

A part (device 100) of a manufacturing apparatus used in the method for producing a glass substrate of the present invention will be described with reference to Fig. 2 . In the melting step T1, molten glass is produced by melting the glass raw material in the melting device 200 to melt it. Further, in the clarification device 300, the gas component contained in the molten glass is released from the molten glass, or the gas component contained in the molten glass is absorbed into the molten glass. For example, the glass raw material contains a composition such as SiO ₂ or Al ₂ O ₃ .

In the forming step T2, the clarified molten glass is supplied to the forming apparatus 500 by the transfer pipe 400, and is formed into a strip-shaped glass plate G1.

In the cutting step T3, the glass sheet G1 is cut into a single piece by cutting in the width direction by a cutting device (not shown). Further, the four sides are cut to a specific size to form a glass substrate G having a product size.

In the end surface processing step T4, the end surface formed by the cutting is processed by the first end surface processing machine 30 shown in FIG. The end faces 33 of the glass substrate G are processed by bringing the first grinding wheel 31 that rotates by a rotating shaft (not shown) into contact with the second grinding wheel 32 on both end faces of the moving glass substrate G. After the end surface 33 of the long side of the glass substrate G is processed, the end surface 33 of the short side is processed. Thereafter, the mirror surface polishing processing of the end surface 33 is performed by the polishing apparatus 40 provided on the second end surface processing machine 34 shown in FIG. Here, a polishing slurry containing a magnetic body is used. The polishing slurry containing a magnetic material refers to a fluid containing a magnetic abrasive grain mainly serving as a polishing particle, or a fluid mainly serving as a carrier for transporting abrasive particles.

Next, a washing step including a step of removing the magnetic body attached to the polishing process in the end surface processing step T4 from the end surface of the glass substrate G will be described.

In the cleaning step T5, the end surface 33 of the glass substrate G subjected to the mirror polishing treatment in the end surface treatment step T4 is cleaned by the end surface cleaning jig 61 by the first end surface cleaning device 60 shown in Fig. 6(a). In the first end surface cleaning device 60, the first end surface cleaning jig 61 is provided on both sides of the glass substrate G conveyed on the conveying roller 62, and the end surface of the cleaning liquid is sprayed from the main surface side end surface side of the glass substrate G. The nozzle 63 is cleaned.

The end surface is cleaned by the second end surface cleaning device 70 shown in FIG. 6(b) by the glass substrate G of the first end surface cleaning device 60. In the second end surface cleaning device 70, the second end surface cleaning jig 64 is provided on both sides of the glass substrate G conveyed on the conveying roller 62.

The glass substrate G on which the end surface 33 of the long side is cleaned by the first end surface cleaning device 60 and the second end surface cleaning device 70 is rotated by 90 degrees and the long side by a reversing machine (not shown). The short side of the glass substrate G is cleaned in the same manner.

Further, after cleaning the four sides of the end surface 33 of the glass substrate G, the main surface of the glass substrate G is cleaned. The surface and the back surface of the glass substrate G are cleaned by the surface cleaning apparatus 80 shown in FIG. 6(c). The cleaning roller 65 is provided on the front side and the back side of the glass substrate G conveyed on the conveying roller 62, and the main surface of the glass substrate G is cleaned by applying an alkaline cleaning agent for the glass substrate. In the present embodiment, the cleaning roller 65 uses a brush roller in combination with a sponge roller to remove organic substances and particles adhering to the main surface of the glass substrate.

In the inspection step T6, the end surface 33 of the glass substrate G and the main surface are inspected, and then shipped to a display panel manufacturer or the like in the form of a glass substrate for display.

Hereinafter, the end surface treatment step T4 and the cleaning step T5 of the present invention will be described in more detail with reference to the drawings. The end surface treatment step T4 of the present embodiment has the first grinding step, the second grinding step, and the polishing step shown in Fig. 4 shown in Fig. 3 .

First, the first end surface processing machine 30 and the second end surface processing machine 34 will be described. As shown in FIG. 3, in the first end surface processing machine 30, the glass substrate G is conveyed in the direction of the arrow, and the first grinding wheel 31 and the second grinding wheel 32 provided at both ends of the glass substrate are used to face the long side. The end faces of the sides are sequentially ground. In addition, after the grinding process is performed on the long side, the grinding process on the short side is performed in the same manner, and the orientation flat processing and the chamfering (not shown) are performed as needed.

The first grinding wheel 31 is a grinding wheel in which diamond abrasive grains are fixed by using a metal-based adhesive containing iron. The hardness and rigidity of the adhesive used in the first grinding wheel are higher than those of the second grinding wheel 32. Here, the hardness means the hardness of the Shore, and the term "rigidity" means the Young's modulus. When the binder of the first grinding wheel 31 is a metal system, other metal binders such as cobalt or bronze may be used. Further, as long as the hardness and rigidity are higher than those of the second grinding wheel, a ceramic binder can be used as the binder of the first grinding wheel 31. The first grinding wheel 31 cases For example, diamond abrasive grains having a particle size of #300 to #400 as specified in JIS R6001-1987 can be used. In the present embodiment, the first grinding wheel 31 is made of diamond abrasive grains having a particle size of #400. The abrasive grains are not limited to diamonds, and may be CBN (boron nitride).

The particle size of the first grinding wheel 31 may be equal to or larger than the particle size of the diamond abrasive grains of the second grinding wheel 32.

The second grinding wheel 32 is a grinding wheel in which diamond abrasive grains are fixed by a resin-based adhesive containing an epoxy resin. The adhesive of the second grinding wheel 32 is a binder which is lower in hardness and rigidity than the adhesive of the first grinding wheel 31. As for the adhesive of the second grinding wheel 32, a ceramic binder can be used as long as the hardness and rigidity are lower than that of the first grinding wheel 31. In the case of a resin system, for example, a polyimide-based material can also be used. The abrasive particles are not limited to diamonds, and may also be CBN. In the present embodiment, the second grinding wheel 32 is a diamond abrasive grain having a particle size of #400 as defined in JIS R6001-1987.

Further, in terms of performing grinding efficiently, the particle size of the abrasive grains of the first grinding wheel 31 is preferably equal to or larger than the particle size of the abrasive grains of the second grinding wheel 32.

In the first grinding step, the end surface 33 of the glass substrate G is ground by a specific grinding amount by the shape formed on the first grinding wheel 31, for example, a grinding groove having a specific curvature. Thereby, the end surface 33 of the glass substrate G retreats from the original end surface 33 to the center side of the glass substrate, and the cross-sectional shape of the end surface 33 is ground into a convex curvature with respect to the cross-sectional shape of the grinding groove of the 1st grinding wheel 31. Shape, arc or R shape. Here, the amount of grinding refers to the distance from the original end surface 33 before the grinding to the apex of the convex end surface 33 after grinding and being retracted. That is, it means the amount by which the end surface 33 of the glass substrate G is ground in the direction of the main surface of the glass substrate G. The amount of grinding of the glass substrate G by the first grinding wheel 31 is, for example, in the range of 40 μm to 80 μm. The transport speed of the glass substrate G in the first grinding step is preferably 10 m/min or more from the viewpoint of ensuring productivity. In the present embodiment, the transport speed of the glass substrate G is 10 m/min.

In the first grinding step, JIS B 0601-1982 of the end face 33 of the glass substrate G is used. The end surface 33 of the glass substrate G is ground to a predetermined maximum height Rmax of at least 10 μm or more and 18 μm or less, more preferably 13 μm or more and 14 μm or less. Further, the arithmetic mean roughness Ra defined by JIS B 0601-1994 of the end surface 33 of the glass substrate G is, for example, about 0.5 μm.

Thereafter, in the second grinding step which is provided after the first grinding step, the end surface 33 is ground by the grinding groove of the second grinding wheel 32 on the glass substrate G. Thereby, the cross-sectional shape of the end surface 33 of the glass substrate G is ground into a convex shape having an curvature, an arc shape, or an R shape in accordance with the cross-sectional shape of the grinding groove of the second grinding wheel 32. In the present embodiment, the grinding groove of the second grinding wheel 32 is substantially the same shape as the grinding groove of the first grinding wheel 31, so that the outer shape of the end surface 33 of the glass substrate G can be changed without changing the outer shape of the end surface 33 of the glass substrate G. The end face 33 of the glass substrate G is ground by a specific amount of grinding.

The amount of grinding of the glass substrate G produced by the second grinding wheel 32 is, for example, in the range of 10 μm to 30 μm. In the second grinding step, the end surface 33 of the glass substrate G is ground so that the maximum height Rmax defined by JIS B 0601-1982 of the end surface 33 of the glass substrate G is at least 4 μm or more and 8 μm or less, more preferably about 6 μm. Moreover, the arithmetic mean roughness Ra of the end surface of the glass substrate G is 0.2 μ or less, for example, 0.1 μm to 0.2 μm.

After the long side of the glass substrate G is processed by the first grinding step and the second grinding step, the orientation of the glass substrate G is rotated by 90 degrees by a reversing machine (not shown), similarly to the long side. The short side of the glass substrate G is processed.

In addition, in the rotation direction of the first grinding wheel 31 and the second grinding wheel 32, the moving direction of the outer peripheral surface of the grinding wheel 31 at the point of contact with the glass substrate G can be set to be the same as the conveying direction of the glass substrate G, Can be set to the opposite direction. In the present embodiment, the moving direction of the outer peripheral surface of the first grinding wheel 31 and the second grinding wheel 32 at the point of contact with the glass substrate G in the first grinding step and the second grinding step is the conveying direction of the glass substrate G. In the opposite direction, the first grinding wheel 31 and the second grinding wheel 32 are rotated in one direction.

In the grinding step, as described above, the cross-sectional shape of the end surface 33 of the glass substrate G is ground into a convex shape, an arc shape or an R shape with curvature, and the arithmetic mean roughness Ra of the end surface 33 of the glass substrate G is performed. Grinding to 0.2 μm or less. However, on the end surface 33 of the glass substrate G which is ground by the first grinding wheel 31 and the second grinding wheel 32 which are diamond grinding wheels, a layer containing minute cracks called microcracks or hairline cracks is formed. This layer is referred to as a work-affected layer or a fragile fracture layer, and is present in a thickness of about 1 μm to 3 μm even after the first grinding step and the second grinding step. Due to the presence of such a layer, the fracture strength of the end face 33 of the glass substrate G is lowered, or the glass is detached from the microcrack. In order to remove such a layer to improve the fracture strength of the end surface 33 of the glass substrate G, the polishing process is performed.

In the polishing step, the work-affected layer or the fragile fracture layer of the end surface 33 of the glass substrate G is removed, and the arithmetic mean roughness Ra of the end surface 33 of the glass substrate G is, for example, less than 0.01 μm, and the glass is ground by the polishing device 40. The end face 33 of the substrate G.

As shown in FIG. 4, the glass substrate G which finished the grinding|polishing of the end surface 33 of the glass substrate of the long side and the short side by the grinding|polishing process is conveyed to the position by the grinding|polishing apparatus 40. Thereafter, the end surface 33 of the glass substrate G is polished by the polishing apparatus 40 attached to the second end surface processing machine 34 shown in Figs. 4(a) and 4(b). Fig. 4(b) is a cross-sectional view taken along line II-II of Fig. 4(a). The polishing apparatus 40 rotates the rotating wheel 36 around the rotating shaft 35. The rotating wheel 36 holds a polishing slurry 37 containing a magnetic body in a gap (also referred to as a magnetic field forming portion) of the disk-shaped magnetic bodies 36a and 36b which are disposed in parallel along the longitudinal direction of the rotating shaft 35.

The end portion 33 of the glass substrate G is immersed in the polishing slurry 37 containing the magnetic body held by the magnetic field formed by the magnetic bodies 36a and 36b, and the rotating wheel 36 is attached to the end surface 33 of the glass substrate G and the polishing containing the magnetic body. The slurry 37 is rotated in contact with it. Thereby, the polishing slurry 37 containing the magnetic material moves relative to the end surface 33 of the glass substrate G, and the end surface 33 of the glass substrate G is brought into contact with the polishing slurry containing the magnetic body bound by the magnetic field formed by the magnetic field forming portion. Grinded.

The shape of the abrasive grains contained in the polishing slurry 37 containing a magnetic material is a polygonal shape having a small roundness or an indefinite shape having a corner portion. The indefinite shape having a corner includes a three-dimensionally inconsistent shape having one or more acute angles. Further, the term "having a corner" includes the case where the particles are thinned toward the edge; the outline of the cross section of the particle forms one or more acute or obtuse angles; and the edges of the particles are sharp. Further, the abrasive grains may be spherical. The spherical shape includes not only a shape in which the cross-sectional shape is a circular shape but also a shape in which the cross-sectional shape is an elliptical shape such as an elliptical shape or an oblong shape. Further, when the abrasive grains in the polishing slurry containing the magnetic material are magnetic abrasive grains, the concentration of the magnetic abrasive grains in the polishing slurry is preferably from 85 to 95% by weight. The higher the concentration of the magnetic abrasive grains, the higher the ability to polish the end faces 33 of the glass substrate G, but on the other hand, the cooling effect by evaporation of water is reduced. Therefore, when the concentration of the magnetic abrasive grains in the polishing slurry is 95% by weight or more, the end surface 33 of the glass substrate G is heated by the processing heat.

After the polishing step, the end surface 33 of the glass substrate G has a top portion A, a boundary portion B and a surface of the end surface and the main surface, and at these portions, the glass substrate G is removed from the processing layer of the end surface 33 or is fragile. The fracture layer was subjected to mirror polishing treatment so that the arithmetic mean roughness Ra was less than 0.01 μm. In particular, when the Ra of the boundary portions B and C is less than 0.01, the generation of the glass frit from the end surface 33 is suppressed, and the adhesion to the main surface of the glass substrate G is reduced. Moreover, the improvement of the bending strength of the glass substrate G can also be achieved.

Further, the glass substrate G may be subjected to end surface polishing in a state of being fixed to the stage, or may be subjected to end surface polishing by moving it to a fixed grinding wheel. Further, the end surface 33 of the glass substrate G may be polished side by side, or a plurality of rotating wheels 36 may be prepared, and a plurality of sides of the end faces 33 of the glass substrate G may be polished. Further, the polishing slurry 37 containing a magnetic material may be a fluid containing magnetic abrasive grains mainly functioning as polishing particles for the magnetic material, or may be a flow of the magnetic body mainly serving as a carrier for transporting the abrasive particles. body.

In addition, the measurement of the amount of removal of the glass substrate G and the surface roughness, that is, the arithmetic mean roughness Ra, was performed using a Surfcom A1400 manufactured by Tokyo Precision Co., Ltd., and the glass substrate shown in FIG. The apex A of the end surface 33 of G and the boundary portions B and C near the boundary between the end surface 33 and the main surface are performed. The measurement of the removal amount of the glass substrate G was performed under the condition that the measurement mode was the cross-sectional measurement mode, the measurement speed was 0.6 mm/s, the tilt correction was the first half correction, and the measurement distance was 20 mm. Further, the measurement of the surface roughness was carried out under the conditions that the measurement mode was roughness measurement, the measurement speed was 0.3 mm/s, and the measurement method was JIS 1994. In addition, the measurement of the arithmetic mean roughness Ra is a cutoff value of 0.08 and a measurement length of 0.4 mm when Ra<0.02, and a cutoff value of 0.25 and a measurement length of 1.25 mm when 0.02<Ra<0.2, at 0.1<Ra< At 2 o'clock, the cutoff value was 0.8 and the measurement length was 4 mm.

Next, the washing step T5 and its washing action will be described. In the present invention, as a method of removing the magnetic body attached to the end surface of the glass substrate G polished by the polishing slurry containing the magnetic material, the magnetic property attached to the end surface of the glass substrate G in a specific pH environment is examined. The surface of the body is ionized, and the surface potential of the end surface of the glass substrate G is made to be a positive potential, the magnetic body is floated from the end surface of the glass substrate G, and re-adhesion is prevented by chelation.

First, in the first end surface cleaning step by the first end surface cleaning device 60 shown in Fig. 6(a), an acidic chemical having a pH of 2 or less, preferably a pH of 1.6 or less is used. The liquid is supplied from the end surface cleaning nozzle 63 to the end surface of the glass substrate G, and ionization of the magnetic body adhered to the end surface of the glass substrate G is performed. Thereby, the electrostatic interaction between the end surface of the glass substrate G whose surface potential becomes a positive potential and the magnetic body is reduced, and the magnetic body is easily separated from the end surface of the glass substrate G. Further, the magnetic body is reliably removed from the end surface of the glass substrate G by physically cleaning with a sponge in a state where the electrostatic interaction between the end surface of the glass substrate G and the magnetic body is reduced.

Further, the chemical liquid supplied to the first end surface cleaning step contains a chemical liquid having a chelate effect on iron in an environment having a pH of 2 or less, thereby sequestering the ionized iron to prevent further Adhered to the surface of the glass substrate G.

As the chemical liquid having a reducing effect, it is preferred to contain an acidic chemical liquid having at least a standard redox potential of -0.35 V or less. For example, the reduction of Fe ³⁺ ions requires -0.77 V, and the reduction potential of Fe ³⁺ ions can be lowered by using a chemical solution having a chelate effect. That is, the reduction effect can be obtained even above the above potential, and the cleaning action of the end faces of the glass substrate G is further improved.

The magnetic body which leaves the end surface of the glass substrate G by physical cleaning is formed into a chelate compound by the magnetic body even if it is placed in a pH environment sufficient to increase the electrostatic interaction between the surface of the glass substrate G and the magnetic body. And preventing the magnetic body from adhering again to the glass substrate G.

Then, in the second end surface cleaning step by the second end surface cleaning device 70 shown in FIG. 6(b), the rinsing for cleaning and removing the magnetic material which becomes a chelate in the first end surface cleaning step is performed. In the second end face cleaning step, it is preferable to try not to bring the magnetic body into the subsequent step. For example, in order to remove the iron component constituting the chelate compound, an acidic chemical liquid having a pH of 2 or less, preferably pH of 1.6 or less is used, and then the chemical liquid used for washing is washed away by washing with pure water. .

The first end face cleaning jig 61 of Fig. 6(a) will be described with reference to Figs. 7(a) and 7(b). Fig. 7(a) shows a part of the end surface of the glass substrate G in the first end face cleaning machine 60. The first end surface cleaning jig 61 has a cleaning pad 61c provided on the support portion 61b that is rotated by the rotating shaft 61a, and cleans both ends of the glass substrate G conveyed by the conveying roller 62.

The end surface of the cleaning pad 61c and the glass substrate G is ejected from the end surface cleaning nozzle 63a with an acidic chemical liquid having a pH of 2 or less, preferably a pH of 1.6 or less. As an example, a mixed liquid of oxalic acid and tartaric acid may be applied to the end faces of the glass substrate G. The cleaning pad 61c contains an acidic chemical liquid that contacts the end surface of the glass substrate G and slides, whereby the end surface of the glass substrate G can be chemically cleaned and physically cleaned, and the magnetic body attached to the end surface of the glass substrate G is separated from the glass substrate. The end face of G. The detached magnetic system is chelated by tartaric acid.

The end surface cleaning jig 61 that is in contact with the end surface of the glass substrate G may be a cleaning roller 611 whose rotation direction is substantially perpendicular to the end surface as shown in Fig. 7(b). Moreover, it can also be like the end face cleaning nozzle 63b The chemical liquid is supplied to the end face from the front direction.

Next, the second end face cleaning device 70 of Fig. 6(b) will be described with reference to Fig. 7(c). The glass substrate G of the first end surface cleaning device 60 is introduced into the second end surface cleaning device 70, and the chemical solution liquid of the previous step is washed away by the second end surface cleaning jigs 64a and 64b.

FIG. 7(c) shows a part of the end surface of the glass substrate G in the second end surface cleaning device 70. In the second cleaning step, the chelating magnetic body is washed away by the rinsing liquid until the surface cleaning device of the subsequent step, and the pH value of the acidic chemical liquid adhered to the glass substrate is lowered, and the acidic chemical liquid is suppressed. Take the next steps.

As shown in FIG. 7(c), the second end face cleaning jig 64 has cleaning nozzles 64a and 64b which are opposed to each other at a specific angle to the end surface of the glass substrate G. First, the end surface of the glass substrate G is rinsed by the first rinse liquid discharged from the cleaning nozzle 64a. The first rinse liquid uses a rinse liquid having a pH equivalent to that of the chemical liquid used in the first end face cleaning step. After the chemical liquid adhered from the first end surface cleaning step is washed away by the first rinse liquid, the end surface of the glass substrate G is rinsed with pure water as the second rinse liquid. Thereby, it is possible to prevent the acidic chemical liquid from being carried into the main surface cleaning step of the glass substrate G by the surface cleaning device 80 shown in Fig. 6(c) which is a later step. Further, by using the chemical liquid having the pH equivalent to the first end surface cleaning step for the first rinse liquid, the magnetic body is surely washed away.

Further, in the present embodiment, a cleaning nozzle that ejects the rinsing liquid on the side of the abutting surface of the autonomous surface may be provided on the main surface side of the glass substrate G, and a cleaning nozzle that ejects the rinsing liquid from the front side of the end surface may be provided.

In the method for producing a glass substrate for a display of the present invention, it is preferable that the valence electron number of iron is Fe ²⁺ and a complex compound is formed. Therefore, it is preferable to add oxalic acid having a strong reducing property to the first end face. The acidic chemical liquid used in the cleaning device 60 is used.

Regarding the stability of the complex, when the electron number of iron is Fe ³⁺ , the stability is higher than that of Fe ²⁺ . However, in the case where the iron-based fine particles peeled off from the end surface of the glass substrate G are Fe ³⁺ , when the Fe ³⁺ is not completely sequestered, in the above-described rinsing step, compared with Fe ²⁺ The Fe ³⁺ iron-based fine particles are easily passivated on the main surface and the end surface of the glass substrate G to cause re-adhesion.

Therefore, in the present invention, since the possibility that the magnetic body is not sequestered remains, the rinsing step of removing the complex of the magnetic material from the glass substrate G before the main surface cleaning step is performed, even if it is cleaned. The pH of the liquid changes from acidic to neutral, and also inhibits the magnetic body from adhering to the main surface of the glass substrate G to be passivated.

That is, according to the present invention, the following effects are achieved: By constituting the magnetic body Fe ³⁺ is reduced to Fe ^2+, Fe ³⁺ and compared, by the washing step of the present invention inhibit the major surface of the glass substrate G Re-adhesion caused by passivation.

The chelating agent used in the present invention is preferably a chelating agent which is coordinated to a bidentate or more. Specifically, it is preferable that the iron ion center having a six-coordinated position from the regular octahedron of Fe has a molecular structure of an electron-donating group at a distance of 3 Å or less in the xyz-axis direction.

As a specific example, the above chemical solution having a chelation effect is preferably selected from the group consisting of salicylic acid, phthalic acid, glyoxylic acid, oxalic acid, fumaric acid, maleic acid, malonic acid, and amber. Organic acids such as acid, gluconic acid, trans-aconitic acid, hydroxymalonic acid, lactic acid, pyruvic acid, citric acid, isocitric acid, glycolic acid, malic acid, tartaric acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, An aminocarboxylic acid such as hydroxyethylethylenediaminetriacetic acid or diethylenetriaminepentaacetic acid, or one of a group consisting of amino acids such as serine, aspartic acid, glutamic acid, and cysteine The above is particularly preferably two or more.

In the above, the embodiment of the present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the spirit and scope of the invention.

[Examples]

Hereinafter, embodiments of the invention will be described in detail.

(Examples 1 to 5) and (Comparative Examples 1 to 3)

First, the polishing slurry-based magnetic material containing a magnetic material used for polishing the end surface of the glass substrate mainly serves as a flow body containing the magnetic abrasive grains as the polishing particles. The magnetic body of the magnetic abrasive grain-based ferrite system is characterized in that the shape of the particles is an indefinite shape having a corner portion, the average particle diameter is 5 μm or more and 10 μm or less, the maximum magnetic flux density is 1.3 T, and the maximum magnetic permeability is 3.0. Abrasive particles of the magnetic body of H/m. Next, a polishing slurry is prepared by mixing the prepared abrasive particles with water. As an example, the magnetic abrasive grains are preferably mixed with water so that the concentration of the abrasive grains in the polishing slurry is 85 to 95% by weight.

In the present embodiment, the concentration management of the magnetic fluid is performed using wt% in consideration of the ease of management and the suitability for mass production, but the concentration management of the magnetic fluid can also be carried out using vol%. The conversion between wt% and vol% can be calculated based on the bulk specific gravity of the magnetic abrasive grains and the density of water of 1 g/cm ³ . Further, in the present embodiment, the amount of water evaporated is added to the polishing slurry in consideration of evaporation of water in the polishing slurry containing the magnetic body in the polishing process. Specifically, a polishing slurry containing a magnetic material obtained by mixing magnetic abrasive grains and water is supplied to a rotating wheel that polishes an end surface of a glass substrate at a predetermined interval. The polishing slurry containing the magnetic material is supplied at a lower concentration than the polishing slurry containing the magnetic material held by the rotating wheel.

Magnetic abrasive grains are attached to the boundary portion B and the boundary portion C shown in FIG. 5 on the end surface of the glass substrate obtained by the above-described polishing treatment.

The end surface of the glass substrate was cleaned using the acidic chemical liquid described in "Table 1" below, and the washing result was evaluated. The evaluation results are summarized in Table 1.

Specifically, in Examples 1 to 5, the concentration of the acidic chemical liquid containing an organic acid was adjusted to 2% by weight. Moreover, the operation was performed so that the pH value became 2 or less at the time of washing.

After the end surface polishing of the glass substrate by the magnetic abrasive grains, the cleaning of the end faces is carried out in the following steps.

1) spraying the acidic chemical liquid shown in Table 1 from the nozzle to the end surface of the glass substrate, 2) Washing with a sponge disk impregnated with a chemical liquid, 3) spraying a chemical liquid from the nozzle on the end surface of the glass substrate, and 4) spraying pure water on the end surface of the glass substrate to rinse.

Further, in Examples 1 to 5 and Comparative Examples 1 to 3, a glass substrate having a thickness of 0.5 mm was used.

In the evaluation method, the foreign matter remaining on the end surface of the glass substrate was peeled off by an adhesive jig, and the adhesion amount per unit area was measured. Specifically, the ratio of the remaining area of the foreign matter remaining on the end surface of the glass substrate is attached to the central portion of the four end faces of the glass substrate of each sample, and the transparent tape is peeled off, and the CCD (Charge Coupled Device) is used. The charge-coupled element is an optical microscope of the imaging device to observe the surface of the peeled transparent tape. Further, it is attempted to attach a transparent tape to the entire thickness direction of the processing region of the end surface of the glass substrate (points B to C of Fig. 5).

The observation area by the optical microscope was set to a distance of point B to point C of the end surface of the glass substrate of Fig. 5, that is, a region of 0.75 mm × a length direction of the glass substrate of 0.75 mm. Count the number of foreign objects in the area and evaluate them.

Further, foreign matter attached to the main surface (back surface) of the glass substrate after the cleaning step was also evaluated. Specifically, the amount of foreign matter adhering to the back surface of the glass was measured using a glass substrate surface inspection apparatus (GI4830 manufactured by Hitachi High-Tech Electronics Co., Ltd.). The measurement conditions were measured under conditions of measuring polystyrene standard particles of 1 μm or more.

As shown in Table 1, the surface state of the glass substrate after the cleaning was observed by a laser microscope at points A, B, and C shown in Fig. 5, and the cleaning effect was evaluated. The conditions of the pH value, the reduction effect, and the chelation effect were quantified based on the physical properties of the chemical liquid.

In the examples and comparative examples of Table 1, the acid dissociation constant (pKa) was expressed as ◎ at a pH of 4.4 or less, ◎ at a pH of 4.4 to 6, and × at a pH of not 6. Further, regarding the reducing ability, the electrode potential of the standard hydrogen electrode is set to -0.35 V or less to ◎, -0.35 V to -0.05 V to ◎, and -0.05 V or more to x.

Regarding the cleaning effect, the case where the number of end face particles after cleaning is less than 150 is set to "cleaning effect: high", and the case where the number of pieces is less than 300 is set to "cleaning effect: yes". Moreover, the case of 300 or more is set as "cleaning effect: none."

If the number of foreign matters in the observation area is less than 300, the yield reduction is not caused by the presence of iron-based fine particles in the display manufacturing step. There is no problem in the TFT panel manufacturing steps that are concerned about the influence of iron-based particles. Further, with the glass substrate surface inspection device, foreign matter exceeding 1 μm was not detected from the glass substrate in which the foreign matter did not exceed 300 in the observation area.

As a result of the above Examples 1 to 5 and Comparative Examples 1 to 3, when oxalic acid having an acidity and reducing ability of an organic acid and tartaric acid having a high chelating value were used, a high cleansing effect was confirmed. In Example 4, a particularly high cleaning effect was obtained.

According to the above Examples 1 to 5, it is preferred to use a chemical liquid containing a carboxyl group of an organic acid to adjust the chemical liquid to have a pH at which at least a part of the carboxyl groups are ionized. More preferably, it is a chemical liquid which has a plurality of carboxyl groups and is ionized at a plurality of positions and is adjusted to have a pH lower than the isoelectric point of the glass.

As described above, in one aspect of the present invention, by setting the pH to 2 or less, preferably to a pH of 1.6 or less, the electrostatic interaction between the end surface of the glass substrate and the magnetic body is reduced, and the magnetic body is used as the magnetic body. The iron-based fine particles are ionized to float from the end surface of the glass substrate, and the ionized iron-based fine particles are sequestered, thereby preventing the adhesion to the main surface and the end surface of the glass substrate. Moreover, the cleaning is removed in the rinsing step of the subsequent step. The chemical solution used for the rinsing is preferably set to a pH of 3 or less, or a pH of 2 to 3. However, the chemical solution used for the rinsing may be set to the same pH as the chemical solution used for reduction or chelation.

When an acid having strong oxidizing power such as concentrated nitric acid or concentrated sulfuric acid is used as the acidic chemical liquid, the surface of the iron-based fine particles is passivated, so that the acid having strong oxidizing ability is unsatisfactory.

Further, in the method for producing a glass substrate of the present invention, it is preferred that the valence electron number of iron is Fe ²⁺ to form a complex compound. As far as the stability of the complex is concerned, the stability of Fe ³⁺ is higher than that of Fe ²⁺ with respect to the number of electrons of iron. However, when the iron-based fine particles peeled off from the end surface of the glass substrate are reduced from Fe ³⁺ to Fe ²⁺ , the iron-based fine particles in the rinsing step are present when the Fe ³⁺ is not completely chelated. The surface of the glass substrate is passivated and adhered to the main surface and the end surface of the glass substrate.

Therefore, in the present invention, in the rinsing step of removing the iron complex and removing other foreign matter, even if the pH of the cleaning liquid is changed from the acidic state to the neutral side for the rinsing, the Fe-based fine particles are Fe. ^{3+ is} reduced to Fe ²⁺ , and compared with Fe ³⁺ , the passivation of the main surface and the end surface of the glass substrate can be suppressed, and the iron-based fine particles can be prevented from adhering to the main surface and the end surface of the glass substrate. That is, the iron-based fine particles that have adhered to the end faces of the glass substrate are suppressed from adhering to the main surface.

Further, it is preferable that the chemical liquid having the reducing effect contains an acidic chemical liquid having at least a standard oxidation-reduction potential of -0.35 V or less. The reduction of Fe ³⁺ ions requires -0.77 V, and the reduction potential of Fe ³⁺ ions can be lowered by using a chemical solution having a chelate effect. That is, the reduction effect can be obtained at the above set potential or higher, and the end face cleaning can be performed. Oxalic acid is used in the above examples. Further, since the reduction of Fe ³⁺ ions requires -0.77 V, in order to obtain higher cleaning properties, a chemical liquid having a standard oxidation potential of an acidic chemical liquid of -0.8 V or less is preferably used.

Further, as the chelating agent, a chelating agent which is coordinated to a bidentate or more is preferable. Specifically, it is preferable that the iron ion center having a six-coordinated position from the regular octahedron of Fe has a molecular structure having an electron-donating group at a distance of 3 Å or less in the xyz-axis direction. As a specific example, the above chemical liquid having a chelation effect may be selected from the group consisting of salicylic acid, phthalic acid, glyoxylic acid, oxalic acid, fumaric acid, maleic acid, malonic acid, and succinic acid. , gluconic acid, trans-aconitic acid, hydroxymalonic acid, lactic acid, pyruvic acid, citric acid, isocitric acid, glycolic acid, malic acid, tartaric acid and other organic acids, nitrilotriacetic acid, ethylenediaminetetraacetic acid, hydroxyl One or more of an aminocarboxylic acid such as ethylethylenediaminetriacetic acid or diethylenetriaminepentaacetic acid, or an amino acid such as serine, aspartic acid, glutamic acid or cysteic acid. .

The cleaning of the end faces of the glass substrate is preferably accompanied by physical cleaning. In order to remove the magnetic body peeled off from the end surface of the glass substrate from the end surface, it is preferable to use the cleaning jig which contacts the end surface of the glass substrate in the state containing or holding the chemical liquid, and washes the end surface. For example, a disc-shaped sponge or brush or the like is preferable.

The glass substrate produced by using the present invention is not limited to the use of the display, and can be applied to the production of other glass substrates. Further, it can also be applied to a glass substrate which is wound into a roll-shaped thin plate. The glass substrate wound into a roll shape is cut into both sides of the formed glass plate, and the cut surface of the both sides is processed, and the cut surface is processed and washed.

In the above-described embodiment, the polishing apparatus 40 described in the embodiment and the polishing apparatus 40 described in FIG. 4 is used to perform the glass substrate G by using the polishing slurry 37 containing the magnetic material held between the magnetic bodies 36a and 36b attached to the rotating shaft 35. The mirror polishing process of the end face 33 may be performed by cleaning the glass to be polished by bringing the magnetic abrasive grains into contact with the end faces of the glass substrate. Fig. 8 shows a polishing apparatus 180 of another embodiment. Polishing slurry containing magnetic body The 187 is supplied from the supply unit 184 to the groove of the rotary wheel 182 having a groove (not shown), and the polishing slurry 187 containing the magnetic body is held by the magnetic body 185 provided on the rotary wheel 182. The polishing slurry 187 containing a magnetic body contacts the end surface of the glass plate as it rotates, and is recovered by the recovery portion 186. Moreover, FIG. 4(b) shows a state in which the two magnetic bodies 36a and 36b of the rotating wheel 36 are disposed including the vacant gap (magnetic field forming portion), and the polishing slurry 37 containing the magnetic body is held in the magnetic field forming portion. However, it is also possible to arrange the two magnetic bodies 36a and 36b without leaving a gap. When the two magnetic bodies 36a and 36b are not closely spaced apart from each other, the polishing slurry 37 is held on the outer circumferential surface of the rotating wheel 36 by the magnetic field formed by the rotating wheel 36.

In the above embodiment, a single-chip cleaning method for cleaning the glass substrates G one by one has been described with reference to FIGS. 6 and 7. However, in the cleaning step T5 of the present invention, a batch cleaning system in which a plurality of glass substrates G are simultaneously cleaned may be employed.

Fig. 9 is a cross-sectional view conceptually showing one of a plurality of liquid tanks 700 in a batch cleaning system for simultaneously cleaning a plurality of glass substrates G. The batch cleaning system includes a plurality of liquid tanks 700 shown in FIG. 9 and a transport mechanism that transports cassettes 800 that accommodate a plurality of glass substrates G. Each of the liquid tanks 700 includes an ultrasonic cleaning mechanism that cleans the glass substrate G by ultrasonic waves in a state where the glass substrate G is immersed in the liquid L, and a temperature adjustment mechanism that adjusts the temperature of the liquid L. Further, the batch cleaning system includes a storage tank that supplies the liquid L to each of the liquid tanks 700.

The cassette 800 accommodating the plurality of glass substrates G is transported by the transport apparatus, and is sequentially immersed in the liquid L such as the acidic chemical liquid, the pure water, or the ultrapure water stored in the liquid tank 700. The acidic chemical liquid stored in each of the liquid tanks 700 is added to the diluent obtained by diluting the cleaning agent for the glass substrate G with water, and one or more kinds of acidic acids selected from the group consisting of polybasic organic acids such as oxalic acid, tartaric acid, and citric acid are added. Made with ingredients. When the pH of the acidic chemical solution containing an organic acid is lowered to 2.0 or less, preferably 1.6 or less, the zeta potential of the surface of the glass substrate G becomes a positive potential, and the end surface and the main surface of the glass substrate G are attached. The magnetic body is easy to leave Glass substrate G. Further, the magnetic substance is prevented from adhering to the glass substrate G by the chelation effect of the acidic chemical solution component. By exhibiting these functions of the acidic chemical liquid, the magnetic body to which the glass substrate G is attached can be effectively cleaned.

Further, after washing with an acidic chemical solution, a washing step using an alkaline cleaning solution may be added. As the alkaline cleaning liquid, for example, a solution of potassium hydroxide (KOH) can be used.

[Industry use possibility]

The glass substrate produced by the present invention is not limited to the use of the display, and can be suitably used for display applications. The glass substrate for a display manufactured by using the present invention is not limited to the glass substrate for a TFT panel for driving, and includes, for example, a glass substrate for a color filter or a glass substrate for a cover glass. Further, the display device is not limited to a liquid crystal display or an organic EL display, and may be used for other displays.

Claims (12)

A method for producing a glass substrate, comprising: a method of producing a glass substrate having a processed portion, wherein the processing portion is polished by contact with a polishing slurry containing a magnetic material, and the polishing portion is supplied with cleaning The liquid charges the surface of the processing portion and the surface of the magnetic body attached to the processing portion in the same polarity, and the processing portion and the magnetic body repel each other to move the magnetic body into the cleaning liquid. A method for producing a glass substrate, comprising: a forming step of forming a glass plate from molten glass; a cutting step of cutting the glass plate to form a glass substrate; and an end surface treatment step of causing the magnetic body The held polishing slurry containing the magnetic material is subjected to mirror polishing to the end surface of the glass substrate, and the cleaning step is performed by using an acidic chemical liquid having a pH of 2 or less to clean the iron system generated by the magnetic body contacting the end surface The microparticles are characterized in that the cleaning step is characterized in that Fe ³⁺ constituting the iron-based microparticles is reduced to Fe ²⁺ ions, and a complex compound is formed by coordination of the bidentate or more of the Fe ²⁺ ions. The method for producing a glass substrate according to claim 2, wherein the acidic chemical solution contains two or more kinds of chemical liquids, and the chemical liquid contains a chemical liquid having a chelation effect. The method for producing a glass substrate according to claim 2 or 3, wherein the cleaning step includes a cleaning jig for physically cleaning the end surface in contact with the end surface. The method for producing a glass substrate according to claim 3, wherein the chemical liquid having the chelate effect has an electron source from a six-coordinated iron ion center of the regular octahedron of Fe, and has an electron supply distance of 3 Å or less from the xyz axis direction. The molecular structure of the base. The method for producing a glass substrate according to claim 3, wherein the chemical liquid having the chelation effect is selected from the group consisting of salicylic acid, phthalic acid, glyoxylic acid, oxalic acid, fumaric acid, maleic acid. , malonic acid, succinic acid, gluconic acid, trans-aconitic acid, hydroxymalonic acid, lactic acid, pyruvic acid, citric acid, isocitric acid, glycolic acid, malic acid, tartaric acid, nitrilotriacetic acid, ethylenediamine One or more of the group consisting of tetraacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, serine acid, aspartic acid, glutamic acid, and cysteine. The method for producing a glass substrate according to claim 6, wherein the chemical liquid having the chelating effect is selected from the group consisting of oxalic acid, tartaric acid and citric acid, wherein the concentration is adjusted to 0.5% by weight or more. The method for producing a glass substrate according to claim 2, wherein the step of the cleaning step includes a first rinsing step and a second rinsing step, wherein the first rinsing step uses a chemical solution having a pH of 3 or less, and the second portion A chemical solution having a pH of more than 3 is used in the rinsing step. A method for manufacturing a glass substrate for a display, comprising: a forming step of forming a glass plate from molten glass; a cutting step of cutting the glass plate to form a glass substrate; and an end surface treatment step by a polishing slurry containing a magnetic body held by the magnetic body is subjected to a mirror polishing treatment in contact with an end surface of the glass substrate; a cleaning step of cleaning the end surface with an acidic chemical liquid; and the end surface treatment step is characterized by using a grinding wheel, The grinding wheel includes: a magnetic field forming portion having a first magnetic body and a second magnetic body that rotate together with the rotating shaft, and a magnetic abrasive grain and a liquid, and is formed between the first magnetic body and the second magnetic body a polishing slurry containing the magnetic material held by the magnetic field, wherein the polishing slurry containing the magnetic body is brought into contact with an end surface of the glass substrate while rotating the rotating shaft; and the cleaning step is characterized in that In the end surface treatment step, the magnetic abrasive grains adhered to the end surface of the glass substrate are produced. The iron-based fine particles are used, and the Fe ³⁺ constituting the iron-based fine particles is reduced to Fe ²⁺ ions by using an acidic chemical liquid having a pH of 1.6 or less, and two or more of the Fe ²⁺ ions are coordinated to form a fault. Compound. The method for producing a glass substrate for a display according to claim 9, wherein the end surface treatment step has a grinding treatment for grinding an end surface of the glass substrate before the mirror polishing treatment, and the grinding treatment is characterized in that the polishing is fixed by using a first adhesive. Grinding the first grinding wheel of the abrasive grain, grinding the end surface of the glass substrate, and grinding the abrasive grain with the second adhesive having a lower hardness and rigidity than the first adhesive after the first grinding process The second grinding process for grinding the end surface of the glass substrate by the second grinding wheel is characterized in that the concentration of the magnetic abrasive grains in the polishing slurry is 85 to 95% by weight. The method for producing a glass substrate for a display according to claim 10, wherein the first binder is a metal binder, and the second binder is a resin binder. The method for producing a glass substrate for a display according to claim 10, wherein in the grinding process, the end surface of the glass substrate is ground to an arithmetic mean roughness Ra defined by JIS B 0601-1994 to be 0.2 μm or less, and the mirror surface is polished. During the treatment, the end faces of the glass substrates were polished until the arithmetic mean roughness Ra was less than 0.01 μm.